Evidence accumulated over the past several decades suggests that diet and physical activity and the outcomes of those behaviors, overweight and obesity, contribute to 30-40% of cancer cases. Further, diet and physical activity can make an important contribution to cancer management across the cancer continuum, affecting prognosis and long-term survival. Disentangling the effects of diet, physical activity, obesity and associated lifestyle factors is challenging. A major challenge in this area of research is the recognized limitations in the traditional methods of diet and physical activity assessment. Also, sustained changes in eating and activity behaviors that may reduce cancer risk and progression are most likely to be achieved when evidence-based behavioral and technological strategies are applied. With cancer research efforts increasingly focused on the energy balance and adiposity, the resource scope has expanded in this submission to offer state-of-the-art physical activity and body composition measurements and monitoring. The Diet and Physical Activity Shared Resource provides services in four areas: dietary assessment and monitoring, including the collection and analysis of dietary data utilizing a variety of approaches, and the development of food content databases and biomarker/biochemical laboratory analysis; behavioral/lifestyle coaching and intervention-related services targeting diet, physical activity, and weight loss; physical activity and sedentary behavior assessment including objective measurements of physical activity and sedentary behavior, using accelerometers and other state-of-the-art tools and technologies; and body composition analysis, including regional fat and lean mass, using dual-energy x-ray technology. Objectives of this shared resource are to enable Cancer Center members to have access to state-of-the-art services provided by individuals with expertise in these specialized disciplines, diet and physical activity assessment and behavior change, and thus to contribute to the core scientific mission that defines the primary goals of the Center. Since the prior CCSG review, the resource has contributed to scientific efforts in numerous major grants and projects.